Brain sigma receptors are the subject of intense investigation in light of the fact that sigma receptors bind many psychotropic drugs (Sonders et al., Trends Neurosci. 11: 37-40 (1988)). Moreover, certain sigma receptor ligands have antipsychotic activity which suggests that sigma receptor active compounds may be used for the treatment of schizophrenia (Largent et al., Eur. J. Pharmacol. 11: 345-347 (1988).
Certain neuroleptic (i.e. antipsychotic) agents bind with very high affinity at sigma sites. Su, T., J. Pharmacol. Exp Ther. 223: 284 (1982); Tam, S. W., Proc. Nat. Acad. Sci (USA) 80: 6703 (1983). One agent with very high affinity for sigma sites (Ki ca 1 nM; i.e., approximately 100-fold higher affinity than N-allyl normetrazocine (NANM)) is the neuroleptic agent haloperidol. Tam, S. W. et al., Proc. Nat. Acad. Sci (USA) 81: 5618 (1984). Sigma-opiates, such as NANM, bind with low affinity at typical opiate receptors but bind with significant affinity at PCP receptors.
Current neuroleptic agents are thought to produce their effects via a dopaminergic (DA) mechanism; they display very high affinities for DA binding sites. However, not all of the potent neuroleptic agents bind at [.sup.3 H]NANM-labelled sigma sites, nor do the sigma-opiates bind at DA sites. This has led to the suggestion that the sites labelled by [.sup.3 H]NANM be termed sigma-sites and not sigma-opiate sites (i.e., it may simply be coincidental that the sigma opiates possess an opiate-like chemical structure). In addition, there has been speculation that agents with high affinity for sigma sites may either (a) produce psychotic effects (if they behave as agonists), or (b) produce antipsychotic effects (if they behave as antagonists). It has further been speculated that certain neuroleptic agents, such as haloperidol, produce their antipsychotic effects by both a sigma and DA mechanism. Tam, S. W. and Cook, L., Proc. Nat. Acad. Sci. (USA) 81: 5618 (1984). In fact, [.sup.3 H]haloperidol, in combination with spiperone (an agent with high affinity for DA sites and essentially no affinity for sigma sites) is now commonly used to label sigma sites in radioligand binding studies.
A number of researchers have studied the structure-activity relationship of sigma ligands. For example, Manallack, D. T. et al., Eur. J. Pharmacol. 144: 231-235 (1987), disclose a receptor model for the phencyclidine and sigma binding sites. Manallack et al. disclose that in a recent SAR study (Largent et al., in press), sigma site affinity was shown to be enhanced by large N-alkyl substituents, e.g., benzyl or phenethyl.
Largent, B. L. et al., Mol. Pharmacol. 32: 772-784 (1987), disclose a study of the structural determinants of sigma receptor affinity. In particular, Largent et al. teach that several piperidine and piperazine derivatives have sigma receptor activity. Largent et al. also disclose that affinity for the sigma receptor is markedly influenced by the N-alkyl substituents, with more lipophilic substituents affording greater affinity for the sigma receptor binding sites.
Sharkey, J. et al., Eur. J. Pharmacol. 149: 171-174 (1988), studied the sigma receptor binding activity of cocaine-related compounds.
The literature contains a number of suggestions that the sigma receptor is not a single, homogeneous binding site. Bowen, W. D. et al., Eur. J. Pharm. 163: 309-318 (1989), disclose that the effect of U.V. radiation on sigma receptor binding depended on the radioligand used to assay for it. It was also demonstrated that the binding characteristics of several sigma ligands were different in membranes from certain cell lines than in guinea pig brain membranes. (Hellewell, S. B. and Bowen, W. D., Brain Res. 527: 224-253 (1990); Wu, X.-Z. et al., J. Pharmacol. Exp. Ther. 257: 351-359 (1991)). At least two groups have reported significantly different pharmacology for "sigma receptors" when using different radioligands to label these sites. (Itzhak, Y. et al., J. Pharmacol. Exp. Ther. 257: 141-148 (1991); Karbon, E. W. et al., Eur. J. Pharm. 93: 21-27 (1991)). In addition, [.sup.3 H]DTG binding was found to have two components in guinea pig membranes (Rothman, R. B. et al., Mol. Pharm. 39: 222-232 (1991)). An overlap of sigma sites with some of the multiple sites labeled by [.sup.3 H]dextromethorphan has also been described (Musacchio, J. M. et al., Life Sci. 45: 1721-1732 (1989)).
Hellewell and Bowen, Brain Res. 527: 224-253 (1990), were the first to define the characteristics of the two putative sigma receptor substypes, named sigma-1 and sigma-2. The primary pharmacological distinction between these tow sites is the affinity of the (+) isomers of the benzomorphan opiates for the binding sites. These compounds, such as (+)SKF 10,047 and (+)pentazocine show nearly two orders of magnitude higher affinity for the sigma-1 site compared to the sigma-2 site. The (-) isomers of the benzomethorphans show little selectivity between these two sites. Other distinctions noted between the two sites are a preponderance of the sigma-2 sites in cell lines such as NCB-20, PC12 and NG108-15 cells (Hellewell, S. B. and Bowen, W. D., Brain Res. 527: 224-253 (1990); Wu, X.-Z. et al., J. Pharmacol. Exp. Ther. 257: 351-359 (1991); Georg, A. and Friedl, A., J. Pharmacol. Exp. Ther. 259: 479-483 (1991); Quirion, R. et al., Trends in Pharmacological Sciences 13: 85-86 (1992)).
There has been considerable research on amphetamine and amphetamine derivatives. For example, Aldous, F. A. B., J. Med. Chem. 17: 1100-1111 (1974), discloses a structure-activity study of psychotomimetic phenylalkylamines. Aldous et al. also disclose a number of halo, methyl, and methoxy substituted amphetamines.
Fuller, R. W. et al., J. Med. Chem. 14: 322-325 (1971), disclose amphetamine derivatives substituted on the 3- and 4-positions of the aromatic ring with one or more chloro, fluoro, alkyl, phenoxy, alkoxy and hydroxy substituents.
Foye, W. O. et al., J. Pharm. Sci. 68: 591-595 (1979), disclose heterocyclic analogues of amphetamine having 2-furyl, 2-thienyl, 3-methyl-2-phenol, 3-pyridyl, 6-methyl-2-pyridyl, 4-chlorophenyl, and 1-naphthyl rings.
Boissier, J. R. et al., Chem. Abstr. 66: 46195h (1967), disclose N-benzyl amphetamine derivatives of the Formula (I): ##STR1## wherein X is methyl, CF.sub.3, methoxy, or a halogen and R is hydrogen or methyl. These compounds reportedly have anoretic activity and low toxicity. Particular compounds disclosed by Boissier et al. include N-(1-phenyl-2-propyl)-4-chlorobenzylamine, N-(1-phenyl-2-propyl)-4-methylbenzyl-amine, and N-(1-phenyl-2-propyl)-4-methoxybenzylamine.
Boissier, J. R. et al., Chem. Abstr. 67: 21527a (1967), disclose amphetamine derivatives of the Formula (II): ##STR2## wherein R.sup.1 is hydrogen, 4-Cl, 3-Cl, or 3-CF.sub.3 and R.sup.2 is 2-chlorophenyl, 4-chlorophenyl, 4-bromophenyl, 3-CF.sub.3 -phenyl, 4-tolyl, 4-methoxyphenyl, phenyl, 2-furyl, 2-tetrahydrofuryl, 2-thienyl, or 3-thienyl. Reportedly, these compounds were tested for anorexigenic activity in rats and dogs.
Osbond, J. M. et al., Chem. Abstr. 69: 51816c (1968), disclose N,N-bis-(omega-phenylalkyl)amines having the Formula (III): ##STR3## wherein R.sup.1, R.sup.2, and R.sup.3 are hydrogen, chloro, CF.sub.3, or methoxy.
Gosztonyi, T. et al., J. Label. Comp. Radiopharm. 8: 293-303 (1977), disclose the preparation of N-substituted omega-haloalkyl derivatives of p-chloro amphetamine. Also disclosed, is the corresponding omega-hydroxyalkyl amine.
Coutts, R. T. et al., Can. J. Microbiol. 26: 844-848 (1980), disclose N-substituted p-chloro amphetamines having the following Formula (IV): ##STR4## wherein R.sup.1 is 2-butanone-3-yl, 2-hydroxybutane-3-yl, 1-hydroxybutane-3-yl, or acetate.
Fuller, R. W. et al., J. Pharm. Pharmacol. 5: 828-829 (1973), disclose lipid-soluble derivatives of amphetamine comprising 2-chloro, 3-chloro, 4-chloro, and beta, beta-difluoro-amphetamine, and the effect thereof on amphetamine levels in the brain.
Fuller, R. W. et al., Neuropharmacology 14: 739-746 (1975), disclose 4-chloroamphetamine, 4-bromoamphetamine, and 4-fluoroamphetamine and the effect thereof on serotonin metabolism.
Conde, S. et al., J. Med. Chem. 21: 978-981 (1978), disclose thiophene analogues of chloroamphetamine having the following Formula (V): ##STR5## wherein X, Y, and Z are chloro or hydrogen, and the effect thereof on serotonin levels in the brain.
Lukovits, I., Int. J. Quantum. Chem. 20: 429-438 (1981), discloses various halo, methyl, and methoxy ring-substituted amphetamines, and the inhibitory potencies thereof on phenylethanolamine-N-methyl transferase.
Law, B., J. Chromatog. 407: 1-18 (1987), discloses amphetamine analogues comprising 1-methyl-2-(2'-naphthyl)ethylamine, N-isopropyl-2-(2'-naphthyl)ethylamine, and N-isopropyl-2-phenylethylamine.
Johansson, A. M. et al., J. Med. Chem. 30: 602-611 (1987), disclose N-substituted 2-aminotetralins of the Formula (VI): ##STR6## wherein R.sup.1 is OH or OMe and R.sup.2 and R.sup.3 are H or C.sub.1 -C.sub.4 lower alkyl. These compounds were tested for dopamine receptor agonist and antagonist activities.
Hacksell, U. et al., J. Med. Chem. 22: 1469-1475 (1979), disclose N-alkylated-2-aminotetralins of the Formula (VII): ##STR7## wherein R.sup.1 is OH or OMe, R.sup.2 is lower alkyl, and R.sup.3 is lower alkyl or phenethyl. In particular, Hacksell et al., disclose two aminotetralins of the Formulae (VIII) and (IX): ##STR8##
These compounds reportedly have dopamine-receptor stimulating activity.
McDermed, J. D. et al., J. Med. Chem. 18: 362-367 (1975), disclose N-alkyl aminotetralins of the Formula (X): ##STR9## wherein R.sup.1 and R.sup.2 is one of a large number or alkyl, heteroalkyl, and alkaryl groups. In particular, McDermed et al. disclose two compounds of the Formula (XI) and (XII): ##STR10## These compounds are reportedly dopamine receptor agonists.
Glennon, R. A. et al., Pharmacol. Biochem. Behav. 21: 895-901 (1984), disclose that 2-aminotetralin is a conformationally restricted analog of amphetamine which is about one-half as effective as racemic amphetamine.
Beaulieu, M. et al., Eur. J. Pharmacol. 105: 15-21 (1984), disclose N,N,-disubstituted 2-aminotetralins of the Formula (XIII):
______________________________________ #STR11##
______________________________________ 5-OH H H 5-OH H C.sub.3 H.sub.7 5-OH C.sub.3 H.sub.7 C.sub.3 H.sub.7 - 5-OH C.sub.3 H.sub.7 #STR12## - 5-OH C.sub.3 H.sub.7 #STR13## - 5-H C.sub.3 H.sub.7 C.sub.3 H.sub.7 - 5-H C.sub.3 H.sub.7 #STR14## - 5,6 OH H H 5,6 OH C.sub.3 H.sub.7 C.sub.3 H.sub.7 ______________________________________
These compounds are reportedly potent D-2 dopamine receptor agonists.
Naiman, N. et al., J. Med. Chem. 32: 253-256 (1989), disclose 2-(alkylamino)tetralin derivatives of the Formula (XIV): ##STR15## wherein R is H, OMe, or OBz;
R.sup.1 is H, Me, or n-Pr; and PA1 R.sup.2 is H, n-propyl, benzyl, phenethyl, or phenpropyl. PA1 R is hydrogen or C.sub.1 -C.sub.6 alkyl; PA1 R.sup.1 is independently selected from the group consisting of hydrogen, C.sub.1 -C.sub.6 alkyl, hydroxy, amino, C.sub.1 -C.sub.6 alkylamino or .dbd.O (a double bonded oxygen); or PA1 R and R.sup.1 together form a morpholino ring; PA1 n is 0-5; PA1 W is --(CH.sub.2).sub.p -- or --H H--, wherein p is 1-3; PA1 X is --(CH.sub.2).sub.q --, wherein q is 1-6; PA1 Z is hydrogen, aryl, an aryl-substituted carboxylic acid group, heteroaryl or cycloalkyl, wherein aryl, heteroaryl and cycloalkyl can be substituted by hydrogen, halogen such as chloro, fluoro, bromo, iodo; CF.sub.3, C.sub.1 -C.sub.6 alkoxy, C.sub.2 -C.sub.6 dialkoxymethyl, C.sub.1 -C.sub.6 alkyl, cyano, C.sub.3 -C.sub.15 dialkylaminoalkyl, carboxy, carboxamido, C.sub.1 -C.sub.6 haloalkyl, C.sub.1 -C.sub.6 haloalkylthio, allyl, aralkyl, C.sub.3 -C.sub.6 cycloalkyl, aroyl, aralkoxy, C.sub.2 -C.sub.6 carboxylic acyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, C.sub.3 -C.sub.6 heterocycloalkyl, C.sub.1 -C.sub.6 alkylthio, C.sub.1 -C.sub.6 alkylsulfonyl, C.sub.1 -C.sub.6 haloalkylsulfonyl, C.sub.1 -C.sub.6 alkylsulfinyl, C.sub.1 -C.sub.6 haloalkylsulfinyl, arylthio, C.sub.1 -C.sub.6 haloalkoxy, amino, C.sub.1 -C.sub.6 alkylamino, C.sub.2 -C.sub.15 dialkylamino, hydroxy, carbamoyl, C.sub.1 -C.sub.6 N-alkylcarbamoyl, C.sub.2 -C.sub.15 N,N-dialkylcarbamoyl, nitro, C.sub.2 -C.sub.15 dialkylsulfamoyl or an ortho methylene dioxy group; PA1 U is selected from the group consisting of hydrogen, halogen such as chloro, fluoro, bromo, iodo; PA1 CF.sub.3, C.sub.1 -C.sub.6 alkoxy, C.sub.2 -C.sub.6 dialkoxymethyl, C.sub.1 -C.sub.6 alkyl, cyano, C.sub.3 -C.sub.15 dialkylaminoalkyl, carboxy, carboxamido, C.sub.1 -C.sub.6 haloalkyl, C.sub.1 -C.sub.6 haloalkylthio, allyl, aralkyl, C.sub.3 -C.sub.6 cycloalkyl, aroyl, aralkoxy, C.sub.2 -C.sub.6 acyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, an aryl ring fused to a substituted benzene ring, a substituted aryl ring fused to a benzene ring, a heteroaryl ring fused to a benzene ring, a substituted heteroaryl ring fused to a benzene ring, C.sub.3 -C.sub.6 heterocycloalkyl, a C.sub.3 -C.sub.6 heterocycloalkyl ring fused to a benzene ring, C.sub.1 -C.sub.6 alkylthio, C.sub.1 -C.sub.6 alkylsulfonyl, C.sub.1 -C.sub.6 haloalkylsulfonyl, C.sub.1 -C.sub.6 alkylsulfinyl, C.sub.1 -C.sub.6 haloalkylsulfinyl, arylthio, C.sub.1 -C.sub.6 haloalkoxy, amino, C.sub.1 -C.sub.6 alkylamino, C.sub.2 -C.sub.15 dialkylamino, hydroxy, carbamoyl, C.sub.1 -C.sub.6 N-alkylcarbamoyl, C.sub.2 -C.sub.15 N,N-dialkylcarbamoyl, nitro and C.sub.2 -C.sub.15 dialkylsulfamoyl; PA1 R.sup.5 is hydrogen or hydroxy; and PA1 X, Y and Z are defined above, PA1 b is 1-8; PA1 R is as defined above; PA1 --(CH.sub.2).sub.r --CH.dbd.CH--(CH.sub.2).sub.r --; ##STR41## --(CH.sub.2).sub.r --Y--(CH.sub.2).sub.r --, wherein Y is O or S; or C.sub.1 -C.sub.6 alkyl (wherein Z is hydrogen); PA1 and R.sup.2, V, X, and Z are defined as above. PA1 --(C.sub.2).sub.r --C.tbd.C--(CH.sub.2).sub.r --, wherein each r is 0-3 independently; PA1 --(CH.sub.2).sub.r --CH.dbd.CH--(CH.sub.2).sub.r --; ##STR44## --(CH.sub.2).sub.r --Y--(CH.sub.2).sub.r --, wherein Y is O or S; or C.sub.1 -C.sub.6 alkyl (wherein Z is hydrogen); PA1 X is --(CH.sub.2).sub.q --, wherein q is 3-6; PA1 --(CH.sub.2).sub.r --C.tbd.C--(CH.sub.2).sub.r --, wherein each r is 0-3 independently; ##STR46## --(CH.sub.2).sub.r --Y--(CH.sub.2).sub.r --, wherein Y is O or S; or C.sub.1 -C.sub.6 alkyl (wherein Z is hydrogen); PA1 X is --(CH.sub.2).sub.r --C.tbd.C--(CH.sub.2).sub.r --, wherein r is 0-3; PA1 X is --(CH.sub.2).sub.r --C.tbd.C--(CH.sub.2).sub.r --, wherein each r is 0-3 independently; PA1 U is selected from the group consisting of hydrogen, halogen such as chloro, fluoro, bromo, iodo; PA1 CF.sub.3, C.sub.1 -C.sub.6 alkoxy, C.sub.2 -C.sub.6 dialkoxymethyl, C.sub.1 -C.sub.6 alkyl, cyano, C.sub.3 -C.sub.15 dialkylaminoalkyl, carboxy, carboxamido, C.sub.1 -C.sub.6 haloalkyl, C.sub.1 -C.sub.6 haloalkylthio, allyl, aralkyl, C.sub.3 -C.sub.6 cycloalkyl, aroyl, aralkoxy, C.sub.2 -C.sub.6 acyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, an aryl ring fused to a substituted benzene ring, a substituted aryl ring fused to a benzene ring, a heteroaryl ring fused to a benzene ring, a substituted heteroaryl ring fused to a benzene ring, C.sub.3 -C.sub.6 heterocycloalkyl, a C.sub.3 -C.sub.6 heterocycloalkyl ring fused to a benzene ring, C.sub.1 -C.sub.6 alkylthio, C.sub.1 -C.sub.6 alkylsulfonyl, C.sub.1 -C.sub.6 haloalkylsulfonyl, C.sub.1 -C.sub.6 alkylsulfinyl, C.sub.1 -C.sub.6 haloalkylsulfinyl, arylthio, C.sub.1 -C.sub.6 haloalkoxy, amino, C.sub.1 -C.sub.6 alkylamino, C.sub.2 -C.sub.15 dialkylamino, hydroxy, carbamoyl, C.sub.1 -C.sub.6 N-alkylcarbamoyl, C.sub.2 -C.sub.15 N,N-dialkylcarbamoyl, nitro and C.sub.2 -C.sub.15 dialkylsulfamoyl; PA1 X, Y and Z are defined above, PA1 R.sup.5 is hydrogen or hydroxy; and PA1 X, Y and Z are defined above, PA1 b is 1-8; PA1 R is hydrogen or C.sub.1 -C.sub.6 alkyl; PA1 R.sup.2 is independently selected from the group consisting of hydrogen, chloro, fluoro, bromo, iodo, CF.sub.3, C.sub.1 -C.sub.6 alkoxy, C.sub.2 -C.sub.6 dialkoxymethyl, C.sub.1 -C.sub.6 alkyl, cyano, C.sub.3 -C.sub.15 dialkylaminoalkyl, carboxy, carboxamido, C.sub.1 -C.sub.6 haloalkyl, C.sub.1 -C.sub.6 haloalkylthio, allyl, aralkyl, C.sub.3 -C.sub.6 cycloalkyl, aroyl, aralkoxy, C.sub.2 -C.sub.6 carboxylic acyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, C.sub.3 -C.sub.6 heterocycloalkyl, C.sub.1 -C.sub.6 alkylthio, C.sub.1 -C.sub.6 alkylsulfonyl, C.sub.1 -C.sub.6 haloalkylsulfonyl, C.sub.1 -C.sub.6 alkylsulfinyl, C.sub.1 -C.sub.6 haloalkylsulfinyl, arylthio, C.sub.1 -C.sub.6 haloalkoxy, amino, C.sub.1 -C.sub.6 alkyl-amino, dialkylamino, hydroxy, carbamoyl, C.sub.1 -C.sub.6 N-alkylcarbamoyl, C.sub.2 -C.sub.15 N,N-dialklcarbamoyl, nitro and C.sub.2 -C.sub.15 dialkylsulfamoyl; PA1 --(CH.sub.2).sub.r --CH.dbd.CH--(CH.sub.2).sub.r --; ##STR61## --(CH.sub.2).sub.r --Y--(CH.sub.2).sub.r --, wherein Y is O or S; or C.sub.1 -C.sub.6 alkyl (wherein Z is hydrogen); PA1 and R.sub.2, V, X, and Z are defined as above.
These compounds reportedly bind to the .sup.5 -HT.sub.1A receptor site.
Beecroft, R. A. et al., Tetrahedron 41: 3853-3865 (1985), disclose N,N-disubstituted piperazines having the Formulae (XV)-(XVIII): ##STR16##
Fuller, R. W. et al., J. Pharmacol. Exp. Therapeut. 218: 636-641 (1981), disclose substituted piperazines having the following Formulae (XIX) and (XX): ##STR17## which reportedly act as serotonin agonists and inhibit serotonin uptake or serotonin oxidation.
Fuller, R. W. et al., Res. Commun. Chem. Pathol. Pharmacol. 29: 201-204 (1980), disclose the comparative effects on 5-hydroxyindole concentration in rat brain by p-chloroamphetamine and 1-(p-chlorophenol)piperazine having the following Formulae (XXI) and (XXII): ##STR18##
Boissier, J. et al., Chem. Abstr. 61: 10691c, disclose disubstituted piperazines having the Formula (XXIII): ##STR19## wherein R.sup.1 and R.sup.2 are aryl and X is a straight or branched chain alkylene of C.sub.1 -C.sub.3. The compounds are reportedly adrenolytics, hypotensors, potentiators of barbiturates, and depressants of the central nervous system.
Roessler, Chem Abstr. 61: 13328g, disclose piperazine derivatives of the Formula (XXIV): ##STR20## wherein R.dbd.H or methoxy and R.sup.1 .dbd.H, o-ethylphenyl, or p-chlorophenyl.
Ruschig, H et al., Chem. Abstr. 53: 3253e, disclose a large series of N,N-disubstituted piperazines including 1-benzyl-4-(3-chloro-4-methylphenyl)piperazine.
Shvedov, V. I. et al., Chem. Abstr. 73: 11806q (1970), disclose 4-(R.sup.2 CH.sub.2 --CH.sub.2 substituted)-1-phenyl-piperazines wherein R.sup.2 is phenyl, 2-naphthyloxy, 3-indolyl, 2-methyl-3-indolyl or 2-benzimidazolyl.
Popov, D., Chem. Abstr. 67: 54102m (1967), disclose disubstituted piperazines of the Formula (XXV): ##STR21## wherein R is tolyl, p-methoxyphenyl, m-ethoxyphenyl, beta-naphthyl, m-or p-carboxylphenyl, 3,4-dimethoxyphenyl, 5-hydrindenyl, p-chloro-phenyl, p-bromophenyl, p-iodophenyl, 3,4-dichlorophenyl, and m- or p-nitrophenyl.
Glennon, R. A et al., J. Med. Chem. 31: 1968-1971 (1988), disclose various N,N-disubstituted piperazines having the Formulae (XXVI)-(XXIX): ##STR22##
These compounds reportedly have high affinity for the 5-HT.sub.1A serotonin binding site.
Prasad, R. N. et al., J. Med. Chem. 11: 1144-1150 (1968), disclose N,N-disubstituted piperazines of the Formula (XXX): ##STR23## wherein R.sup.1 is phenyl or o-methoxyphenyl and R.sup.2 is 2,4-dichlorophenyl, o-, m- or p-methoxyphenyl, 3,4-dimethoxyphenyl, or m-tolyl. These compounds are reported to be antihypertensive agents.
Despite the development of the above-mentioned derivatives, a need continues to exist for new sigma receptor ligands and for methods for the treatment of central nervous system disorders.